Flat Rock Minjerribah is an important resting area for one shark species.

There are multiple lines of evidence to support Sand Tiger Sharks regularly and predictably using Flat Rock Minjerribah for resting. Evidence includes scientific surveys and acoustic tracking (Bradford et al. 2025; Otway & Louden 2025), and anecdotal observations from the recreational dive industry. Between 2011–2021, 10-year acoustic transmitters were used to track sharks and determine their preferred habitats based on residency rates (Bradford et al. 2025), and this information was used to determine aggregation sites. Nineteen Sand Tiger Shark aggregation sites have been highlighted in eastern Australia (Bradford et al. 2025). Sand Tiger Shark aggregations were defined as a site where five or more Sand Tiger Sharks are seen aggregating either continuously or on a predictable seasonal cycle, and all were classified as resting areas for the species based on behavioural observations and habitat use.

Sand Tiger Sharks were detected at Flat Rock Minjerribah between June and December, with male sharks mainly detected from June to October, and females detected over two months in June and September (Otway & Louden 2025). Between 2011–2021, nine of the 31 tagged individuals were detected at Flat Rock Minjerribah and observed residence periods lasted up to 15 days (Bradford et al. 2025). Sand Tiger Sharks use Flat Rock Minjerribah as a resting area as part of their annual migration, with the sharks spending more time in the area during the daylight hours, exhibiting a diurnal usage pattern (Otway & Louden 2025). Scientific dive surveys confirmed Sand Tiger Sharks were observed swimming close to the seabed in the area, typical resting behaviour for this species, at a mean depth of 24.9 m (range 18.2–27.0 m). Tagged sharks predominantly swam in gutters near the seabed and did not use shallower water depths at or near the sea-surface (Otway & Louden 2025). The diel patterns in behaviour that the sharks exhibit at these sites is characteristic of Sand Tiger Sharks resting during the day and being active at night (presumably for foraging) (D Harasti pers. comm. 2025). Hovering and milling are also characteristic behaviours of resting Sand Tiger Sharks and comprise the majority of swimming behaviours observed at their main aggregation sites on Australia’s east coast (Smith et al. 2015). When hovering, sharks face into the water current and their tail beats allow them to maintain a stationary position, whereas milling involves slow movements and directional changes generally confined to a particular area within a gutter (Smith et al. 2015).

In addition, between 2013–2021, an acoustic study detected 22 Sand Tiger Sharks (14 males, 8 females) in the area (143,514 detections; Dwyer et al. 2023). Of these, 13 were tagged at Flat Rock Minjerribah (9 males, 4 females) and nine were tagged at Fish Rock in New South Wales (5 males, 4 females). Males used the area for resting for an average of 14.6 days (range = 59 min–59 days), whereas females used the area for an average of seven days per year (range = 38 min–37 days). The study concluded that Sand Tiger Shark seasonal residency in the area is for resting purposes either prior to the mating period (typically November and December; Bansemer & Bennett 2011) or for pregnant females as they move southward to pup (Dwyer et al. 2023).

Between 2018–2025, recreational dives were conducted in the area daily to weekly (D Fitzgerald & T Gray pers. obs. 2025). No formal records were collected from these recreational dives, however, anecdotal observations were made during the years these regular dives took place. Sand Tiger Sharks were observed on ~100% of dives between July–October, with occasional aggregations seen outside this period. On average, ~20 Sand Tiger Sharks are observed on a single 60-minute dive (range 5–40 individuals, depending on conditions and visibility). Sand Tiger Sharks are generally seen aggregating in the gutters around the Shark Alley dive site on the eastern side of the islet. They can be seen swimming slowly, close to the sandy substrates, a typical resting behaviour for this species (T Gray pers. obs. 2025).